Engines, including diesel engines, gasoline engines, gaseous fuel powered engines, and other engines known in the art ignite an air/fuel mixture to produce heat. In one example, fuel injected into a combustion chamber of the engine is ignited by way of a spark plug. Specifically, a high voltage current is directed through an electrode located at a center of the spark plug, from a terminal end to a distal free end. The distal free end is spaced a particular distance from a grounded portion of the spark plug, such that an arc spanning the distance is generated. This arc has sufficient voltage to breakdown and thereby ignite an air and fuel mixture within the combustion chamber.
Although successful at initiating combustion, a spark plug may suffer from a low component life. The spark plug life typically depends on an amount and/or a duration of energy delivered to the spark-plug. For example, the high breakdown voltage requirement of the spark plug's arc can be damaging to the grounded portion of the spark plug. In addition, during a conventional ignition process, the spark plug is usually supplied with energy for a long fixed duration, regardless of whether combustion has already been initiated. That is, the spark plug is struck over and over again (i.e., supplied with a current following a repeating profile) regardless of combustion initiation until the fixed time duration has relapsed. Therefore, in situations where combustion has already been initiated, extra and unnecessary strikes of the spark plug not only waste energy but also detrimentally affect the spark plug life. This may lead to reliability reduction of the spark plug and/or premature replacement of the spark plug to ensure continued operation of the engine.
One attempt at extending the life of a spark plug is described in U.S. Pat. No. 8,078,384 (the '384 patent) that is issued to Glugla et al. on Dec. 13, 2011. The '384 patent discloses systems and methods for controlling an internal combustion engine including determining a presence of charge dilution and selecting a spark restrike mode to provide multiple spark events during a single combustion cycle. Charge dilution is determined based on a commanded air/fuel ratio and exhaust gas recirculation. Multiple spark events are controlled using time-based restrike or current-based restrike in response to the charge dilution, thus improving ignition quality to facilitate extending the spark plug life.
Although the system and method of the '384 patent may improve ignition quality of the spark plug, it may still be sub-optimal. For example, extra and unnecessary strikes may still be performed after combustion has been initiated. This may cause premature wear of the spark plug and cause the spark plug to operate unreliably.
The disclosed ignition control system is directed to overcoming one or more of the problems set forth above.